A novel competition model for describing bacterial growth in mixed culture was developed in this study. Several model candidates were made with our logistic growth model that precisely describes the growth of a monoculture of bacteria. These candidates were then evaluated for the usefulness in describing growth of two competing species in mixed culture using Staphylococcus aureus, Escherichia coli, and Salmonella. Bacterial cells of two species grew at initial doses of 10 Biocontrol Science, 2014, Vol. 19, No. 2, 61 71 Here N is the microbial population at time t. N max and N min correspond to the maximum and the initial cell populations, respectively. m and n are the parameters for the curvature of the deceleration phase and the period of the lag phase, respectively Fujikawa, 2010 .The NL model has been shown to describe and predict microbial growth in broth and on agar plates successfully at constant and dynamic temperatures Fujikawa et al., 2003 andFujikawa and Morozumi, 2005 . It could further predict the amount of s t a p h y l o c o c c a l e n t e r o t o x i n A p r o d u c e d b y Staphylococcus aureus in milk and a blue pigment caused by Pantoea agglomerans on agar plate Fujikawa and Morozumi, 2006;Fujikawa and Akimoto, 2011 . We now consider the NL model to be a